benefit(X,Y) :- b(X,Y0), Y is Y0. 

b(X,Y) :- once(b0(X,What)), b1(What,Y). 

b0(X, oops(var)) 				:- var(X). 
b0(claim2parent(A,B), 	claim2parent(A,B)). 
b0(effect(Roulette=G), 	Out)		:- roulette(Roulette,_), rouletted(effect(Roulette=G), Out). 
b0(effect(E=G), 		effect(E=G)). 
b0(true, 				true). 
b0((A,B), 				(A,B)). 
b0((A;B), 			(A;B)).
b0(X, Op/V/Terms) 				:- X =.. [Logic,Terms], check(logics, Logic), score(Logic,Op,V). 
b0(not A, stakeholder(not A)) 	:- node_info(stakeholder, A, _). 
b0(A, stakeholder(A)) 			:- node_info(stakeholder, A, _). 
b0(A, abduced(not A) ) 			:- choices(A,Ind), memo(Ind,not A,0). 
b0(A, abduced(A) ) 				:- choices(A,Ind), memo(Ind,A,0). 
b0(not A, claused(not A,R)) 	:- choices(not A,Ind), memo(Ind,A,R). 
b0(A, claused(not A,R)) 		:- choices(not A,Ind), memo(Ind,not A,R). 
b0(A, claused(A,R)) 			:- choices(A,Ind), memo(Ind,A,R). 
b0(A, clause_not_lurched(A,_)) 	:- clause(A,_). 
b0(A, unclaused(A)). 

b1(true,Value) :- score(default, Value). 
b1((X,Y), O) :- b(X,O1), b(Y,O2), combine(O1,O2,O). 
% without support of claim, effect of child softgoal to parent is 
b1(claim2parent(effect(_=Claim), _),V):- 
memo(_,not Claim,_), score(wout_claim_support, V). 
b1(claim2parent(Claim, Goal),WWW):- 
b(Goal, W), b(Claim, WW), 
scoring(claim2parent, Arith, V), 
do(Arith, [W,WW], O), do(multiply,[V,O],WWW). 
b1(effect(E=G),Out) :- 
scoring(E,Arith,Val), b(G,V), do(Arith,[Val,V],Out). 
b1(claused(not A,_), W) :- score(not_done,W), not (var(A), complain(?node is not bounded?, A)). 
b1(claused(A,R), WW) :- 
weighting(A,W), 
clause(A,B,R), 
brecorda(current_head, R), 
b(B,X), 
recorded(current_head, R, Ref), erase(Ref), 
scoring(c2p, Arith, V), 
do(Arith, [W,X], O), 
do(multiply,[V,O],WW). 
b1(clause_not_lurched(_A,_), W) :- score(not_lurched, W). 
b1(Op/V/L0,Y) :- maplist(b,L0,L), do(Op,L,Y0), do(multiply,[V,Y0],Y). 
b1(stakeholder(_), V):- score(stakeholder, V). 
b1(abduced(not _),Y) :- score(not_done,Y). 
b1(abduced(A), Y) :- 
weighting(abduced, A, Y). 
b1(unclaused(_), Y) :- score(not_done,Y). 
b1(oops(X), _) :- complain(?Something is wrong at calculating benefit?,X). 

scoring(A,B,D) :- 
score(A,B,C), callable(C), !, call(C,D). 
scoring(A,B,C) :- score(A,B,C). 
weighting(abduced,A,V) :- !, once(weighting1(abduced,A,V)). 
weighting(A,C) :- 
(severity(A,_,S);S=normal),
once(weighting1(S,A,C)). 
weighting1(S,A,C) :- 
weight(S,A,W), callable(W), !, call(W,C). 
weighting1(S,B,C) :- weight(S,B,C). 
pricing(A,B,D) :- 
price(A,B,C), callable(C), !, call(C,D), jot_down(price,B,D). 
pricing(A,B,C) :- price(A,B,C), jot_down(price,B,C). 
combine(V1,V2, Out) :- 
score(combine, C), 
do(C, [V1,V2], Out). 
do(add, L, Sum) :- sum(L, Sum). 
do(min,L,Min) :- min(L,Min). 
do(max,L,Max) :- max(L,Max). 
do(average,L,Av) :- average(L,Av). 
do(multiply,L,O) :- multiply(L, O). 
rouletted(A,B) :- once(rouletted1(A,B)). 
rouletted1(Roulette, Out) :- 
recorded(current_head, Head), 
recorded(Head, Roulette=Out). 
rouletted1(A, clause_not_lurched(A,_)). 
jot_down(A,B,C):- once(jot_down1(A,B,C)). 
jot_down1(Key, Node, Info) :- 
enable_jot_down(Key), 
bassert(jotted_down(Key, Node, Info)). 
jot_down1(_,_,_).